Rise and shine! Neuronal switches have been discovered that can suddenly rouse flies from slumber – or send them into a doze.

There are several parallels between sleep in flies and mammals, making fruit flies a good choice for investigating how we sleep. One way to do this is to use optogenetics to activate specific neurons to see what they do. This works by using light to turn on cells genetically modified to respond to certain wavelengths.

Gero Miesenböck at the University of Oxford and his team have discovered how to wake flies up. Using light as the trigger the team stimulated neurons that release a molecule called dopamine. The dopamine then switched off sleep-promoting neurons in what’s called the dorsal fan-shaped body, waking the flies. Meanwhile, Fang Guo at Brandeis University in Waltham, Massachusetts, and his team have found that activating neurons that form part of a fly’s internal clock will send it to sleep. When stimulated, these neurons released glutamate, which turned off activity-promoting neurons in the master pacemaker area of the brain.